| Multicast is a key technology enabling efficient point to multi-point communications, be they wireless- or wireline-based. Satellite systems, such as Satellite Digital Multimedia Broadcasting (S-DMB), are ideal for multicast due to their inherent wide geographic reach. However, the capacity constraints in satellite systems and the possibility of feedback implosion do not favour the provision of a return channel for user feedback which is a must for providing full reliability in content delivery. Two packet loss mitigation mechanisms that become relevant in this scenario are data carousels and packet-level forward error correction (FEC). The research herein aims to enhance reliable content delivery mechanisms with emphasis on those applicable to S-DMB. The work carried out is divided into three main parts. The first part compares various FEC codes under potential S-DMB burst losses. The simulation results show that one FEC code is the best at protecting all relevant file sizes in sharp contrast to the conventional thinking that small FEC codes are better than large codes at protecting small files, and vice versa for large files. In the second part, two aspects of a FEC code known as two-dimensional Reed Solomon (2D RS) are explored. A number of 2D RS file success rate bounds are derived and compared to simulation results. The comparison demonstrates that two of the derived bounds, an upper and lower, can be used in conjunction to reasonably estimate the real performance of 2D RS without the need for time consuming simulations. A number of 2D RS decoding algorithms are also proposed. The experimental results reveal useful insights for the pursuit of more efficient decoding algorithms, hi the third part, the integration of data carousels and FEC is investigated via analytical and simulation means while considering different content properties, FEC codes, data retrieval techniques, and ways of assigning FEC redundancy to various files on a carousel. The results show that the average content download time can be optimised, and that FEC redundancy is the main factor therein. The investigations herein are different from other works which largely investigate the two schemes separately or are rather limited when they examine the joint scheme. |
